The increased permeability of selected plastic membrane of this invention is classified in Class 210, subclasses 640, 650, 651, 653, 654, 655, 645, 642.
The permeability of thermoplastic membrane to molecules of chemical compounds dissolved in water and to water can be increased by chemically modifying the plastic composition, and also by physically modifying the thermoplastic membrane structure. There are diffusional application needs for requiring selected chemical molecules to migrate through barrier thermoplastic membrane. Other diffusional application needs must provide for diffusion of selected molecules, including water flow across the barrier membrane. The presence of liquid water on one face of the plastic membrane can complicate and change the permeability of gases such as CO.sub.2 and O.sub.2 through plastic membrane, due to intermolecular attraction and absorbtion of water molecules in the plastic membrane.
The rate of molecular transport through a plastic membrane is a function of at least two factors: the chemical structure of the diffusing molecule and the molecular state of the plastic membrane, glassy or rubbery.
The integral artificial kidney unit disclosed, taught and claimed in U.S. Pat. No. 4,173,537 issued Nov. 6, 1979, requires that a blood perfusion unit be fabricated from a thermoplastic composition membrane having a high permeability to the waste product excreta molecules which must be removed from the blood of uremic patients.
Cellulose acetate, in both hollow fiber form and membrane form, has been deacetylated to provide a cellulose type structure having improved permeability to a selected molecular weight range including water, as compared to the original cellulose acetate composition.
A regenerated cellulose membrane is regenerated from a cuproammonium cellulose, forming a thin film structure. The regenerated cellulose membrane is utilized, due to the permeability of the membrane to a range of molecular weights, including water. The regenerated cellulose membrane is not a thermoplastic composition.
In U.S. Pat. No. 4,265,745 issued May 5, 1981, Kawaguchi et al disclose a perma-selective membrane comprising a thin film of a polymeric material prepared by cross linking a polyaddition product between a polyepoxy compound and a polyamino compound having at least two amino groups capable of reacting with epoxy groups with a polyfunctional compound selected from the group consisting of aromatic, hetrocyclic and alicyclic compounds containing at least functional groups selected from acid halide, sulforyl halide, isocyanate and acid anhydride groups, and a process for producing the same. The membrane of this invention is especially useful for desalination of saline or brackish water.
In U.S. Pat. No. 4,263,017 issued Apr. 21, 1981, Kara discloses a permeable membrane utilizing a bi-leaf edge membrane concept and the lay-flat tubing connector concept. The above concepts are shown and claimed in transfer systems including selective transfer in general, including selective transfer of gaseous fluids and liquid fluids, as well as heat transfer.
Marze disclosed in U.S. Pat. No. 4,207,182 issued June 10, 1980, a mixture of at least one non-sulphonated polysulphone and at least one sulphonated polysulphone, this mixture having 10 to 30% by weight of sulphonated polysulphone having a theoretical exchange capacity of from 500 to 1,200 meq/kg.
Popovich, Antiviler and Moncrief in U.S. Pat. No. 4,191,182 issued Mar. 4, 1980, disclose a process and apparatus for continuously separating blood into plasma and cellular component fractions, and returning the latter to the subject in admixture with a makeup fluid, employing a membrane ultrafilter.
Credali and Parrini, in U.S. Pat. No. 3,696,031 issued Oct. 3, 1972, disclose and teach a reverse osmosis process utilizing a semi-permeable membrane polyamide comprising the reaction product of a piperozine with a dicarboxylic acid or acid anhydride.